Megapen-XP Capsule is a combination antibiotic formulation containing Ampicillin 250 mg and Dicloxacillin 250 mg, designed to provide broad-spectrum antibacterial activity against a variety of Gram-positive and Gram-negative pathogens. Ampicillin, a beta-lactam antibiotic, exerts its bactericidal effect by inhibiting bacterial cell wall synthesis, effective against organisms such as Escherichia coli, Haemophilus influenzae, and certain strains of Streptococcus. Dicloxacillin, a penicillinase-resistant penicillin, specifically targets penicillinase-producing staphylococci, including Staphylococcus aureus, by similarly disrupting cell wall synthesis. The synergistic action of these two agents enhances the therapeutic efficacy in treating infections caused by mixed bacterial populations or resistant strains. Megapen-XP is indicated for the management of respiratory tract infections, skin and soft tissue infections, urinary tract infections, bone and joint infections, and other susceptible bacterial infections. It is essential to use this medication under medical supervision, with dosage adjusted according to the severity of infection and patient-specific factors. Caution is advised in patients with a history of hypersensitivity to penicillins or cephalosporins. Common adverse effects may include gastrointestinal disturbances such as nausea, vomiting, and diarrhea. Proper adherence to prescribed dosing schedules is critical to prevent the development of antibiotic resistance.